Debt	6 Months Ended
Jun. 30, 2013
Debt Disclosure [Abstract]
Debt	Debt Senior Secured Revolving Credit Facility As of June 30, 2013, the Company's credit facility, which matures on May 13, 2016, had a borrowing base of $1.4 billion, subject to lender commitments. At June 30, 2013, lender commitments under the facility were $1.2 billion. Borrowings under the credit facility bear interest at either (i) LIBOR plus a margin between 1.50% and 2.50% or (ii) the prime rate plus a margin between 0.50% and 1.50%, in each case, based on the amount utilized. The annual commitment fee on the unused portion of the credit facility ranges between 0.35% and 0.50% based on the amount utilized. As of June 30, 2013, there were $646.0 million in outstanding borrowings under the credit facility and $23.2 million in outstanding letters of credit, leaving $530.8 million in borrowing capacity available under the credit facility. The maximum amount available under the credit facility is subject to semi-annual redeterminations of the borrowing base in April and October of each year, based on the value of the Company's proved oil and natural gas reserves, in accordance with the lenders' customary procedures and practices. The Company and the lenders each have the right to one additional redetermination each year. The semi-annual redetermination in April 2013 did not result in any changes to the borrowing base, lender commitments, or other terms of the credit facility. Maturity of 2014 Notes The Company's 10.25% senior notes due 2014 (2014 Notes) are scheduled to mature on June 1, 2014. As a result, all $205.3 million aggregate principal amount of the 2014 Notes is classified as a current obligation on the Company's Condensed Balance Sheet as of June 30, 2013. The Company's ability to repay or refinance the aggregate principal amount of the 2014 Notes is subject to restrictions contained in the Merger Agreement. See Note 11 to the Condensed Financial Statements. While the Company has not yet determined how it will repay or refinance the 2014 Notes, the Company may do so through multiple methods which it may pursue separately or in combination, including (i) issuing new debt or equity securities and (ii) borrowing under the Company's credit facility, which may require seeking additional availability under the credit facility. If the Company is unable to complete a refinancing, it would be in default under the indenture governing the 2014 Notes, which would also cause the Company to be in default under its credit facility and the indentures governing its other senior notes, and would result in indebtedness outstanding under those agreements to be declared immediately due and payable. In addition, failure to comply with any of the indentures or covenants under the senior notes and credit facility could adversely affect the Company's ability to fund ongoing operations and future capital expenditures, as well as the ability to pay distributions to shareholders.

Debt

Senior Secured Revolving Credit Facility

As of June 30, 2013, the Company's credit facility, which matures on May 13, 2016, had a borrowing base of $1.4 billion, subject to lender commitments. At June 30, 2013, lender commitments under the facility were $1.2 billion. Borrowings under the credit facility bear interest at either (i) LIBOR plus a margin between 1.50% and 2.50% or (ii) the prime rate plus a margin between 0.50% and 1.50%, in each case, based on the amount utilized. The annual commitment fee on the unused portion of the credit facility ranges between 0.35% and 0.50% based on the amount utilized.

As of June 30, 2013, there were $646.0 million in outstanding borrowings under the credit facility and $23.2 million in outstanding letters of credit, leaving $530.8 million in borrowing capacity available under the credit facility. The maximum amount available under the credit facility is subject to semi-annual redeterminations of the borrowing base in April and October of each year, based on the value of the Company's proved oil and natural gas reserves, in accordance with the lenders' customary procedures and practices. The Company and the lenders each have the right to one additional redetermination each year. The semi-annual redetermination in April 2013 did not result in any changes to the borrowing base, lender commitments, or other terms of the credit facility.

Maturity of 2014 Notes

The Company's 10.25% senior notes due 2014 (2014 Notes) are scheduled to mature on June 1, 2014. As a result, all $205.3 million aggregate principal amount of the 2014 Notes is classified as a current obligation on the Company's Condensed Balance Sheet as of June 30, 2013. The Company's ability to repay or refinance the aggregate principal amount of the 2014 Notes is subject to restrictions contained in the Merger Agreement. See Note 11 to the Condensed Financial Statements. While the Company has not yet determined how it will repay or refinance the 2014 Notes, the Company may do so through multiple methods which it may pursue separately or in combination, including (i) issuing new debt or equity securities and (ii) borrowing under the Company's credit facility, which may require seeking additional availability under the credit facility. If the Company is unable to complete a refinancing, it would be in default under the indenture governing the 2014 Notes, which would also cause the Company to be in default under its credit facility and the indentures governing its other senior notes, and would result in indebtedness outstanding under those agreements to be declared immediately due and payable. In addition, failure to comply with any of the indentures or covenants under the senior notes and credit facility could adversely affect the Company's ability to fund ongoing operations and future capital expenditures, as well as the ability to pay distributions to shareholders.